The Collaborative International Dictionary of English v.0.48:

Psychotherapy \Psy`cho*ther"a*py\, n. [Psycho- + therapy.]
   (Med.)
   Psychotherapeutics.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

psychotherapy
    n 1: the branch of psychiatry concerned with psychological
         methods [syn: psychotherapy, psychotherapeutics,
         mental hygiene]
    2: the treatment of mental or emotional problems by
       psychological means